cosmopolitan/libc/log/watch.c
Justine Tunney 0d748ad58e
Fix warnings
This change fixes Cosmopolitan so it has fewer opinions about compiler
warnings. The whole repository had to be cleaned up to be buildable in
-Werror -Wall mode. This lets us benefit from things like strict const
checking. Some actual bugs might have been caught too.
2023-09-01 20:50:18 -07:00

90 lines
3.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/bits.h"
#include "libc/intrin/kprintf.h"
#include "libc/log/backtrace.internal.h"
#include "libc/log/log.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/symbols.internal.h"
#include "libc/sysv/errfuns.h"
#ifdef __x86_64__
static bool __watch_busy;
static void *__watch_addr;
static size_t __watch_size;
static char __watch_last[4096];
void __watch_hook(void);
static dontinstrument inline void Copy(char *p, char *q, size_t n) {
size_t i;
for (i = 0; i < n; ++i) {
p[i] = q[i];
}
}
static dontinstrument inline int Cmp(char *p, char *q, size_t n) {
if (n == 8) return READ64LE(p) != READ64LE(q);
if (n == 4) return READ32LE(p) != READ32LE(q);
for (; n; ++p, ++q, --n) {
if (*p != *q) {
return 1;
}
}
return 0;
}
dontinstrument void __watcher(void) {
if (__watch_busy) return;
__watch_busy = true;
if (Cmp(__watch_last, __watch_addr, __watch_size)) {
kprintf("watchpoint %p changed:\n"
"%#.*hhs\n"
"%#.*hhs\n",
__watch_addr, //
__watch_size, __watch_last, //
__watch_size, __watch_addr);
Copy(__watch_last, __watch_addr, __watch_size);
ShowBacktrace(2, __builtin_frame_address(0));
}
__watch_busy = false;
}
/**
* Watches memory address for changes.
*
* It's useful for situations when ASAN and GDB both aren't working.
*/
int __watch(void *addr, size_t size) {
static bool once;
if (__watch_busy) ebusy();
if (size > sizeof(__watch_last)) return einval();
if (!once) {
if (!GetSymbolTable()) return -1;
if (__hook(__watch_hook, GetSymbolTable()) == -1) return -1;
once = true;
}
__watch_addr = addr;
__watch_size = size;
Copy(__watch_last, __watch_addr, __watch_size);
return 0;
}
#endif /* __x86_64__ */